Single-photon emitters are essential components for quantum communication systems, enabling applications such as secure quantum key distribution and the long-term vision of a quantum internet. Among various candidates, self-assembled InAs/GaAs quantum dots (QDs) remain highly promising due to their ability to emit coherent and indistinguishable photons, as well as their compatibility with photonic integration. In this work, we investigate the impact of post-growth rapid thermal annealing (RTA) on the quantum optical properties of single self-assembled QDs embedded in a p-i-n diode structure. The annealing process induces a controlled blueshift of the emission wavelength by promoting Ga in-diffusion and intermixing. Using resonance fluorescence measurements at cryogenic temperatures (4.2 K), we investigate the single-photon statistics, the emission linewidths, and coherence time T2 of the emitted photons. Our results show that, despite the high annealing temperature of 760∘C, the process does not degrade the optical quality of the quantum dots strongly. Instead, we observe single-photon emission with near transform-limited linewidths, where the dephasing time T2 is only a factor 1.5 above the Fourier-limit T2=2T1. These findings demonstrate that rapid thermal annealing (RTA) serves as an effective tuning method that preserves the key single-photon emission properties and may help reduce undesirable effects such as non-radiative Auger recombination in quantum photonic applications.
@article{arxiv.2507.11108,
title = {Near transform-limited single photons from rapid-thermal annealed quantum dots},
author = {Hendrik Mannel and Fabio Rimek and Marcel Zoellner and Nico Schwarz and Andreas D. Wieck and Nikolai Bart and Arne Ludwig and Martin Geller},
journal= {arXiv preprint arXiv:2507.11108},
year = {2026}
}